Integrated circuit memories are being manufactured having increased storage capacity with reduced minimum feature size. As the storage capacity of an integrated circuit memory increases, and/or the minimum feature size decreases, the possibility of having manufacturing defects in the integrated circuit memory increases, reducing production yields. Redundancy is used to repair defective memory cells in an integrated circuit memory by replacing a defective row or column with a redundant row or redundant column, respectively. The ability to repair a memory that has only a few defective rows or columns can result in substantially increased manufacturing yields.
FIG. 1 illustrates, in block diagram form, a portion of a read data path of a prior art integrated circuit memory 10. Integrated circuit memory 10 includes memory array 12, redundant columns 14, column decoding 16, a plurality of sense amplifiers including sense amplifiers 18, 20, and 22, redundant sense amplifier 24, data multiplexer 26, and I/O fuses 28. Sense amplifiers 18, 20, and 22 represent N sense amplifiers, where N is an integer. For purposes of clarity and simplicity, circuits such as row decoding circuits and output data circuits are not shown. Memory array 12 may include, for example, a plurality of static random access memory cells. To repair a defective column in integrated circuit memory 10, the defective column is not decoded to one a plurality of read global data lines labeled "RGDL.sub.0 ", "RGDL.sub.1 ", through "RGDL.sub.N ". Instead, a redundant column is assigned in its place. When a redundant column replaces a defective column of memory array 12, redundant sense amplifier 24 senses and amplifies a differential voltage from redundant columns 14, and provides the amplified differential voltage to a redundant global data line labeled "HRGDL" in FIG. 1. Data from redundant global data line HRGDL is multiplexed to output data circuits with the regular read global data lines RGDL.sub.0, RGDL.sub.1, and RGDL.sub.N by multiplexer 26 when a redundant column replaces a regular column. I/O fuses 28 are set to indicate which regular read global data line is being replaced. After memory 10 is repaired, when the defective column is addressed, the redundant column is automatically selected in its place invisible to a user.
During a read cycle, data from a redundant column should be provided as quickly as data from a regular column. If data from the redundant column is not provided as fast as data from the regular columns, skewing between the data and, for example, a clock signal may result in incorrect data being read from the memory. As integrated circuit memories become larger, denser, and faster, it becomes more difficult for data from the redundant columns to be provided as fast as data from the regular columns.